Method for packaging dry divided solid materials



Aug. 30, 1966 l. H. STOCKEL ET AL 3,269,428

METHOD FOR PACKAGING DRY DIVIDED SOLID MATERIALS Filed Oct. 10, 1961 5Sheets-Sheet l I VENTORfi. OL 1 5/21; 77 rcHEA/HL. Y [VA/a H.5'Toc/(EL.

Aug. 30, 1966 1. H. STOCKEL ET AL 3,269,428

METHOD FOR PACKAGING DRY DIVIDED SOLID MATERIALS Filed Oct. 10, 1961 5Sheets-Sheet 2 INVENTORS.

0L 1 52 777'CHE/V/7L. BY [l/AEHSTocKEL.

(QwruVAcM ATTORNEYS.

Aug. 30, 1966 l. H. STOCKEL ET AL 3,259,423

METHOD FOR PACKAGING DRY DIVIDED SOLID MATERIALS Filed Oct. 10, 1961 5Sheets-Sheet 3 Aug. 30, 1966 I. H. STOCKEL ET AL 3,269,423

METHOD FOR PACKAGING DRY DIVIDED SOLID MATERIALS 5 Sheets-Sheet 4 FiledOct. 10. 1961 Inna mwhdmziib 1 QGEVQU +IIH| J am rllillll w UnitedStates Patent 3,269,428 METHOD FOR PACKAGING DRY DIVIDED SOLID MATERIALSIvar H. Stockel, New City, N.Y., and Oliver 1R. Titchenal, Rumford,R.I., assignors to St. Regis Paper Company, New York, N.Y., acorporation of New York Filed Oct. 10, 1961, Ser. No. 144,142 Claimspriority, application Belgium, Oct. 24, 1960, 474,115, Patent 596,334 14Claims. (Cl. 141-10) This invention relates to the packaging of drydivided solid material, and more particularly, to methods and apparatusfor fluidizing such material and delivering it into packagingcontainers, such as paper bags, for example, while in a fluidized state.

This application is a continuation-in-part of our copending applicationSerial No. 810,465, filed May 1, 1959.

Constructions of the class described are well known to the art and mucheffort has been expended in the development of various operating methodsand apparatus. One familiar construction that has been utilizedheretofore includes a vertical bin open at the top and having adischarge spout at its lower end. Air is introduced under controlledpressure into the lower end of the bin through an inclined air perviouspad to fiuidize the material in the bin and carry it out through thespout. While this type of appaartus has achieved a certain degree ofcommercial success, it, along with other known apparatus of the classdescribed, has proven to be far from satisfactory in a number ofrespects. For example, it has been found that while known apparatus mayperform reasonably well for one or a relatively small group of drydivided solid materials, no known packer is satisfactory for all suchmaterials or even for more than a few types of material. Accordingly, topackage several different materials, a number of different, costlymachines were necessary.

Additionally, bearing in mind that it is the general object of allpackaging equipment of the class described to obtain good weightresults, as dust-free operation as possible, and good filling sped, allwith as little air as possible, it has been found that in knownfluidizing packers, it is often necessary to sacrifice one or more ofthese objectives in order to obtain desired results with the others, sothat none of the known commercial fluidizing packers is entirelysatisfactory.

It is thought that the failure of the art to produce a suitable packeris due to the fact that many of the presently held theories concerningthe performance of dry divided solid material when fluidized in air fordischarge from packaging machinery, are not entirely correct.

Accordingly, in an effort to develop a method and apparatus of the classdescribed that would not only operate in a satisfactory manner for oneor a relatively small group of materials under various conditions, butwould also prove satisfactory for all dry divided solid materials undera variety of conditions, an extensive program of research anddevelopment was undertaken in which the conduct of .air and materialsunder fluidization was studied. As a result of this undertaking, animproved and expanded theory concerning the nature and conduct offluidized solids as related to packaging was developed and, in order tofacilitate a better understanding of the present invention, will be setforth briefly and in part here.

Consider a particle mass uniformly packed and lying at rest in a bin ofuniform cross-section and open at its top through which it may be fedmaterial to be packed. Each particle is supported against gravity by itsneighboring particles creating a total weight per unit of area, or headof material in the bin. If air is caused to flow upward through thevoids between the particles from a uniform supply of air enteringthrough the bottom of the bin, the

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air flow will drag upward upon the particles and thus help to supportthem. The greater the air flow, the greater the support. There is avolumetric air flow rate (c.f.m.) for which the upwardly acting dragsupport on each particle just balances its downwardly acting weight.This is called the point of incipient fluidization, or the criticalvolumetric air flow rate. The pressure drop through the material forthis critical volumetric air flow rate may be termed the criticalpressure drop. For volumetric air flow rates less than this criticalvalue, support of the particles is shared by drag and contactingneighboring particles; for volumetric air flow rates greater than thecritical value, the drag support overbalances gravity and the particlesmomentarily move upwardly. As a result. of this upward movement, theparticle mass occupies a larger volume in the bin, and the void spacebetween particles is increased; therefore, the air velocity need notincrease. The column expands until the increased volumetric air flowrate above such critical rate causes no increase in velocity immediatelysurrounding and supporting a particle. Additionally, the pressure dropthrough the head of material remains very nearly constant above thecritical volumetric air flow rate.

In fluidizing a material, with a volumetric air flow rate equal to orgreater than critical air flow rate, an air pressure is obtained in thematerial at the bottom of the column which is equal to the head ofmaterial, that is, the weight of the material in the column per unit ofcolumn cross-sectional area. What is important here is that this head ofmaterial is not developed by the particles of material resting uponother particles, but rather that an apparent head of material isdeveloped in the manner described wherein the material throughout thecolumn is fluid-like in behavior, that is, easily deformed and ready topass through a filling spout into a bag, for example.

From the foregoing, it will be seen that the air pressure required atthe bottom of a column of material to fluidize that column is thefluidized density of the material times the height of the column. It issomewhat more complicated to determine the critical volumetric air flowrate for a given material since this depends not only upon the materialdensity but also upon particle size distribution and shape distribution.Since, for direct determination, a tedious microscopic examination isnecessary, a simple experiment is recommended. Air flow rate isincreased in an open bin until there is insignificant or no furtherincrease in pressure in the bin, indicating that the critical volumetricair flow rate has been reached.

If now we open a discharge spout adjacent the bottom of the bin, we findthat the apparent head of material in the column due to the pressure ofparticle supporting air will cause material and air to flow out of thebin through the spout. The material flows downwardly in the bin and thusreduces the upward air velocity below that at which it moved upwardlywhen the spout was closed. In fact, if material down flow velocity islarge enough, the air may stand still or even flow downwardly.Therefore, it follows that maintenance of fluidization of downflowingmaterial may require less air flow through the pad at the bottom of thebin than does fluidization of a stationary column, and quite often noair flow is required through the pad.

The foregoing discussion has assumed an ideal material. In practice, itis often found that initial voids vary from one region to another in thebin, and air does not flow uniformly through the material. Or, thematerial may be partially bound, plugged or bridged so that as thecritical point is reached, some of the material expands, but boundportions of the material are partially supported by wall friction. Theexpanded material, being lighter, causes a smaller pressure drop toexist across itself than that which would occur with ideal material.Unfortunately, this smaller pressure drop further starves the boundregion so that additional increases in total fiow only further expandthe lighter expanded material, and further starve the bound material.Thus, the condition is self-aggravating. In time, agitation may wear thebound material away, but considerable time may be required for this; or,on the other hand, the extent to which the majority of air flow maylocalize varies from the mild extent already described, to an extreme inwhich a nearly material-free channel develops which may occupy less than1% of the bin cross-section but carry over 90% of the air. Dischargeunder these conditions could be practically free of material or, in theevent of a plugged tube, no discharge might occur for a period of time.

Furthermore, when dealing with an actual material, it 'has been foundthat even if a rather ideal state of fluidization is achieved, theparticles, in their slightly agitated state, may happen to group moreclosely than average at a particular region of the bin, and maymomentarily bind. This very local condition can, depending purely uponchance, aggravate itself until considerable material has become involvedso that the previously described large scale redistribution of air flowresults. Conversely, the material particles at a location in the binmay, in their agitated state, so move quite by chance as to create alocal diluted region through which the air flow short circuits, therebystarving adjoining regions. Once again, a condition is created which canaggravate itself. The latter two situations clearly assist one another,so that it is unimportant which one occurs first.

Another condition that may exist in practice comes about when the volumeof air flow is much greater than the critical value. Here, the columnboils, that is, much of the air passes up through the material asrelatively large air bubbles. Because this bubbling action causesconsiderable agitation, and because there is a large surplus of airflow, the other aforementioned behaviors are much less likely to occur.The state of the material everywhere, except for the small amount ofdust in the bubbles, is one of fluidity.

Each of the conditions mentioned, except the last, may occur at any timeand reduce the performance of the packer. These conditions reduce thepressure above the pad, and therefore, reduce the effective head, thepurpose of which is to provide a pressurized air-material mixture at thebottom of the column. Due to these conditions, the material feedingthrough the filling spout may be partially bound or overly dilute. Ifpartially bound, the filling rate may be reduced; if overly dilute,excessive air and wild material enter the package, providing the basicfactor in a dirty operation.

To insure total fluidization, it is tempting to employ the lastcondition, namely, bubbling or boiling due to greatly increased airflow. But this condition readily leads to excessive dilution and a dirtyoperation, longer filling times, high bag pressures, and a generallyunstable cycle.

What is desired then, is the elimination of the firstnamed conditionswithout resorting to the last-named condition, such solution beingapplicable to all materials of the class described under a Wide range ofdesired conditions.

In essence then, the present invention resides in the provision of amethod and apparatus that fulfills the aforementioned need; there beingprovided such method and apparatus which is relatively simple, and yet,is successful in eliminating the foregoing difliculties anddisadvantages.

As a most important feature of the present invention, there isintroduced into the column of material a secondary supply of air. Thissecondary supply is located above the primary pad at the bottom of thebin. As a result of this secondary air supply, excessive air flow ratecan be obtained through the material in the column above the primarypad, while only critical flow rate or less than critical flow rate needbe introduced through the primary pad. Excessive air above the region ofthe primary pad insures a fluidized state, while the critical airthrough the material in the bottom of the bin provides relativelycompact, but fluid material in the region just before it flows throughthe discharge or package filling spout. In accordance with their featureof the invention, the secondary air supply will be so positioned thatthe material does not have time to destabilize on its way to the spout,and also that the material density can increase to the desired highvalue before it enters the spout.

The utilization of this secondary air supply quite naturally introducedthe desirability of going to higher pressures to (1) decrease bagfilling time through small filling spouts, and (2) eliminate thepossibility of a condition wherein the pressure at the bottom of the binapproaches that of the bag, that is, the creation of a back pressurewhich would materially reduce or stop flow into the bag. But to increasethe pressure with an atmospheric packer, that is, one that is open atthe top, would mean increasing the height of the bin substantially whereit is desired to package a dry divided solid material, this being due tothe weight per unit of volume of the materialmost such material weighingbetween thirty-five and sixty-five pounds per cubic foot. On the otherhand, if it became necessary to reduce the height of the bin, theobtainable pressure drop through the bin would be proportionally reducedfor the same air flow rate. Therefore, to utilize the higher pressures,the height of the bins must be materially increased. This, of course, isnot desirable since higher bins are more costly and require a greaternumber of secondary air supply means. Furthermore, since theseatmospheric bins are loaded at the top, higher bins necessitate liftingof the material charge to a higher level and this often involves morecostly equipment. There is, therefore, a need for a low head closed binpacker capable of utilizing during bag filling low to relatively highpressure ranges (2-15 p.s.i.g., for example).

Accordingly, another important feature of the present invention residesin the utilization of a bin that is of considerably lower height thanknown atmospheric or open type packers but that is capable of utilizingsuch relatively high pressure range. Packers having bins of the lowenclosed type are subdivided into the batch infeed type and thecontinuous infeed type. The latter bin may be fed continuously throughknown types of continuous feeding devices, such as auger or star valvetypes of feeding apparatus, and, while such a packer of fluidized drydivided solid materials has proven satisfactory, nevertheless, it doespresent the problem of leakage of pressurizing fluid through the feedingvalves. While this problem can be minimized by the introduction ofsufficient secondary air to replace that which is lost in packaging aswell as through the feed mechanism, the leakage becomes more of aproblem as the valve wears and as higher pressures are used.

Therefore, another feature of the present invention resides in theapplication of secondary air to the closed bin low head batch typepackers that may be opened to atmosphere between each bag filling cyclein order to take in a new charge of material, but which are closed toatmosphere during the actual filling of the bag. This type of packerpackages batches of material between charges, and since continuousfeeding is not required, a good, tight seal of the material chargingvalve may be effected between charges.

In packers of the closed bin batch type, the secondary air not onlyprovides the energy level required to discharge fluidized materialthrough a bag filling spout, but also replaces the air that moves out ofthe bin during packaging, and thus all or almost all of the air fed intothe bin during bag filling in this type of packer is such secondary air.Accordingly, merely enough air flow for material fiuidizing or less(even zero flow) is fed during bag filling into the bin via said primaryair source at the bottom region of the bin, and above it is fed suchsecondary air which thus accomplishes the aforementioned pressure changein the bin during bag filling (2-15 p.s.i.g., for example). It should benoted that the time lost during recharging of the bin is negligiblesince the packer is shut down while bags are changed, in any event.While this type of packer requires a slightly larger head than that ofthe continuous feed type, generally it is only necessary for the bin tohave a capacity of 1 to 1 /2 bags of any given material.

The expression energy level as used herein refers in the atmospheric oropen bin type of packer to the pressure of the air or gas surrounding aparticle of material in the region inside the bin near the outlet to thefilling spout. Such air or gas pressure is symbolic of a function ofsaid energy level of the divided solid material and air or gas mixture.There is in the atmospheric type of packer, as its name suggests,substantially atmospheric pres sure at the top region of the bin. Butnear the bottom of the bin there is substantially higher air pressuresurrounding the particles, attributable to the air fed through saidpervious pad or air filter. Hence in the atmospheric type of bin thereis a pressure differential between the pressure of the air surrounding aparticle near the bin outlet to the spout and the pressure of the airsurrounding a particle near the top or in the top region of the bin.However, in the closed pressurized or low head type of bin, when suchbin is closed, the pressures of the air near the outlet and also in thetop region thereof are substantially the same, and hence there is nopressure gradient between these two locations.

Another aspect of the invention contemplates the utilization in bins ofthe enclosed type, of a vent valve. It is often desirable to vent thebins just before the spout is closed to minimize dusting (blowback)problems. In the low head, continuous feed type packer, ventingnaturally takes place through the feeding mechanism, but a vent valve isdesirable nevertheless to assure adequate venting. In the batch typepacker, such a valve may also be used to evacuate the package throughthe bin just before the spout is shut, so as to minimize dusting(blowback) problems, or such a value may be used to vent the bin beforeopening it to its feeding apparatus so as to prevent an explosion intothe feeder. Such a vent valve may also be used to lower the head towardsthe end of each filling cycle to obtain dribble feed into the package,thereby giving fine weight control. Another function for this vent valveis to enable bin pressure to be raised to a relatively high value beforeopening the discharge or filling spout and then quickly dropping thepressure to operating pressure simultaneously with opening of the spoutto obtain an explosion effect in the bin, thus obtaining excellentfluidity.

Where such a vent valve is employed, means may be provided wherebyventing takes place to the supply bin so that any material ventedthrough the valve is not lost, but is ultimately fed back to the bin.

A further feature of this invention resides in the utilization of thisvent valve as a cut-off device. When packaging certain materials, it hasbeen found that by quickly venting the bin, the flow of material fromthe bin into a bag can be stopped or cut ofi substantiallysimultaneously with actuating of the vent valve. In such cases it isunnecessary to provide a filling spout cut-off mechanism or theattendant cut-oft" mechanism control equipment. Of course, the fillingspourt cut-off mechanism may be retained for use during clean-out of thebin, in which case it can be manually operable.

Another feature of the present invention resides in the concept of socontrolling the movement of the bag seat as to enable the same to beutilized to assure full opening of the bag. In this connection, itshould be noted that one of the problems of the industry is that ofincomplete opening of the bags because of the stiffness of the paper,stiff bottoms on pasted bags, and sometimes because the bottoms arepasted closed. Then, as the bag is being filled, the material beingpacked piles up in the bag above the portion of the inner Walls that arepasted together until a suflicient weight of material is so accumulatedto break the bond. At this point, the accumulated material drops to thebottom of the bag and its impact tilts the scale beam to indicate a fullbag when, in fact, the bag is only partially filled. Since the positionof the scale beam is frequently used to control the operation of thepacker, the bag will be improperly discharged as full. The presentinvention contemplates means for assuring full opening of the bag.

Still a further feature of the present invention resides in the bindesign wherein the primary air pad may be disposed lower than thefilling spout. The lower region of the bin may be conical, for example,with the primary pad adjacent the conical surface and the filling spoutabove such surface. This provides better distention of air in the lowerregion of the bin and facilitates the provision of a clean out openingat the bottom or apex of the conical lower bin region. The bin may bereadily cleaned out and its contents conveyed to the supply bin or otherdesirable location by closing the spout and vent, pressurizing the bin,and opening the clean-out opening.

There has thus been outlined rather broadly the most important featuresof the present invention in order that a detailed description thereofthat follows may be better understood and in order that the presentcontribution to the art may be better appreciated. There are, of course,additional features of the invention that will be described hereafterand which will form the subject of claims appended hereto. Those skilledin the art will appreciate that the conception on which the presentdisclosure is based may readily be utilized as the basis for designingthe other structures for carrying out the several purposes of thisinvention. It is important, therefore, that the claims be regarded asincluding such equivalent constructions as do not depart from theconcept and scope of this invention.

A specific embodiment of the invention has been chosen for purposes ofillustration and description and is shown in the accompanying drawings,forming a part of the specification, wherein:

FIG. 1 is an elevational view, partially broken away, to reveal theinterior of the bin of an atmospheric type packer in accordance with thepresent invention and illustrating the filling spout inserted throughthe valve of a FIG. 2 is an elevational view showing a low head typepacker with continuous feed means;

FIG. 3 is an elevational view of a batch type packer in accordance withthe invention and showing an overall arrangement of the packer and thebag weighing means as it might be used in relation to any of the varioustypes of packers;

FIG. 4 is a schematic view of a pneumatic control circuit for the packershown in FIG. 3 and illustrating the condition of the circuit when acycle of operation is initiated; and

FIG. 5 is a schematic view of the circuit shown in FIG. 4 but showingthe condition of the circuit when a stop signal has been initiated;

FIG. 6 is a graphical representation of bin air pressure plotted againstvolumetric air flow rate with respect to that embodiment of theinvention having a bin open to the atmosphere;

FIGS. 7 and 8 are schematic representations in side elevation of apacker as described in connection with FIG. 6 and indicating twodifferent conditions therein;

FIG. 9 is a graphical representation of bin air pressure plotted againsttime in an embodiment of the invention wherein the bin is closed to theatmosphere during the time of the filling of a container andillustrating several novel aspects of this embodiment;

FIG. 10 is also a graphical representation of bin air pressure plottedagainst time showing on a single graph curves typifying the operation ofthe embodiment which is closed and pressurized during the filling of thecontainer and also the embodiment which is open to the atmosphere duringsuch filling of the container.

Referring now to the drawings in detail, there .is shown in FIG. 1 apacker 10 of the atmospheric type, that is, one that is open toatmosphere at its top, comprising a bin 11 having an outlet opening 12adjacent its bottom. The bottom of the bin may be conical in shape andmay have a conduit 14 connected to its apex. A valve 15 is provided inthis conduit for a purpose to be later described.

The outlet opening 12 is connected to a filling spout 16 by a flexiblesleeve or pinch tube 17 which may be squeezed shut to stop the flow ofmaterial through the spout by a cut-off device 19 of known construction.

A pneumatically operable bag clamp assembly 20 of a known type ismounted above the spout to engage a bag 21 in the region of its valveand clamp the same against the spout.

It will be understood that in the various embodiments of the inventionillustrated, any suitable bag clamping and spout flow control device maybe utilized, as such devices per se constitute no part of the presentinvention.

As has been mentioned, the bottom of the bin 11 may be of conical shape.A primary air pad 22, which may be similarly shaped, is spaced slightlyfrom the conical bottom of the bin, thus forming a subchamber 24therebetween and the pad 22 is preferably formed of any suitable airporous material. Fluidizing air under pressure is admitted to thesubchamber 24 through a pipe 25.

Near the top of the bin, 21 secondary air pipe 26 enters the bin andconnects with a secondary air pad 27 which, as shown, may be in the formof a cylinder having its longitudinal axis coincident with the axis ofthe bin. This secondary air pad is essentially an air porous mufiierand, as shown, may be made in sections 29 that interfit, as by screwthreads, so that any desired number of sections may be used. The primaryand secondary air control means Will be described in connection with theembodiments of the invention to be discussed hereinafter. It isnecessary at this point to understand that the air flow rates throughboth the primary and secondary pads can be maintained at levels suitablefor the particular materials being packaged, whereby the primary pad 22can supply the critical flow to establish incipient fluidization at thebottom of the bin, thus providing relatively oompact, flowable materialin the region of the bin adjacent the filling spout, while the secondaryair pad 27 can supply excessive air flow, that is, flow in excess ofcritical to insure a fluidized state, thus preventing the binding,plugging, bridging or channeling of the material above the secondary padwithout resorting to boiling in which the material entering the fillingspout will be overly dilute. It will also be understood that thesecondary air pad will be located low enough so that the material doesnot have time to de-stabilize on its way to the filling tube, but highenough so that the material density can increase to the desired highvalue before it enters the filling spout.

Referring now to FIG. 2, there is shown a low head packer comprising abin 41 that is substantially smaller in its vertical dimension, than isthe bin 11 of the packer 10.

In this embodiment of the invention, the bin is shown with an inclinedbottom 42, by way of example, and spaced therefrom is a primary air pad44 providing a subchamber 45 therebetween that is fed air through a pipe43. The bin also has an outlet opening 46 which may be connected to aspout 16 through a sleeve 17 in the same fashion as is the outletopening 12 of the bin 11 already referred to. In this connection it willbe seen that a suitable cut-off device 19 is used to control flowthrough the outlet opening and a bag clamp 20 is also used, asdescribed, to clamp the bag in fill position.

This packer is provided with a top plate 45a that closes the bin toatmosphere. The plate 45a, however, has a feed opening 46a connected toan infeed conduit 47 leading from a hopper 49. This conduit 47 isprovided with any suitable feed valve 56, such as the start valve shown,for effecting the continuous feed into the bin 41 of material to bepackaged.

The secondary air pad is here shown as a horizontally disposed mufiler51 to which is connected a secondary air pipe 52.

The flow rates in the primary and secondary air pads for each type ofpacker may, for example, be controlled by feeding the air supply throughtwo variable orifices for each pad. Thus, as shown in FIG. 2, each ofthe air supply lines 43 and 52 is forked to form lines 43a, 43b and 52a,5212, respectively. Each line 43a and 43b is supplied through a doubleorifice assembly 54 having chambers 55 and 56, each of which has avariable orifice 57, 59, respectively, in a portion therein. Thevariable orifices are set manually by control knobs 57a and 59a. A mainair supply line 61b delivers air through branch lines 60a and 60b to thechambers 55 and 56, a valve 61 being provided to control the flowthrough one branch or the other.

The branches 52a, 52b of secondary air supply line 52 are each connectedto a chamber of a double orifice assembly 62 that is similar to doubleorifice assembly 54, a valve 64 controlling the flow of air from supplyline 60 to one chamber or the other.

Valves 61 and 64 are preferably controlled through links 61a and 64alinked to a rod 65 that is connected to a piston 66 reciprocable in anair cylinder 67, though other means may be used.

A complete description of the operation of the various embodiments ofthe invention will be presented later, but for the present it should beunderstood that the cylinder 67 will be connected in the pneumaticcontrol system so that the valves 61 and 64 will operate at desiredpoints in the filling cycle to control the flow of air through the airpads. In each case, the setting of the orifices will depend upon thematerial being packed and, as an example of the relationship of primaryand secondary air flow control in a given cycle, the cylinder 67 may beconnected in the pneumatic circuit to operate with the filling tubecut-01f mechanism to reduce the air to both primary and secondary padsas the machine is filling or the cut-off is open; or, it may be desiredto increase flow through the secondary pad while decreasing fiow throughthe primary pad as flow through the filling tube is cut otf; thusmaintaining a pressure level during down time and eliminating the needto build up a head after the filling spout is opened. In any event, itwill be seen that the fiow rates through the pads may be readily variedat desired points in the filling cycle by diverting the air through onechamber or another of the orifice assemblies 54 and 62 by means of thevalves 61 and 64, respectively. Also, for some materials, it may bedesired to shut off one of the air pads at say the filling tube cut-01fpoint in the cycle. When packing such material, one of the orifices inthe supply line to that pad is closed, and at filling tube cut-off theappropriate valve directs air to the chamber in the orifice assemblycontaining that closed orifice, thus cutting off the air fiow to thepad. It will be appreciated by those persons skilled in the art, thatsuch an air supply control system provides universal control and enablesthe packers of the present invention to be utilized for an extremelywide range of materials not heretofore able to be packed in asatisfactory manner by a single packer.

As has already been mentioned, the invention contemplates theutilization of a vent valve in bins of the enclosed type.

Accordingly, as shown in FIG. 2, a pipe 69 containing such a valve 70extends from the top plate 45a of the bin 41 to a suitable level in thehopper 49. The valve 70 is normally in the closed position, but may beopened, for

example, just before the spout is shut to drop the pressure in the binto effect dribble feeding at the spout. While in continuous feed packerssome venting naturally takes place through the feed mechanism, it isdesirable to provide a vent valve to assure proper venting. It will benoted that any material that passes out of the bin through the ventvalve is fed back to the hopper 49 so that the use of such a valveinvolves no waste.

Turning now to FIG. 3, there is shown a batch type packer 75, that is, apacker that is opened to atmosphere between each bag filling cycle inorder to take in a new charge of material. The bin, of course, is closedto atmosphere during the actual filling operation.

The packer includes a bin 76 mounted on -a suitable frame 77 and formedwith an outlet opening 79 adjacent its bottom. The outlet opening 79leads through a flexible sleeve 17 to a filling spout 16 as in theembodiments of the invention already discussed. A filling spout cutoffdevice 19 is provided for shutting off the flow of material through thefilling spout as each bag is filled. A bag clamp device 20 is alsoprovided to clamp the bag to the spout during filling.

As is well known in the art, the filling spout 16 and bag clamp 20 maybe mounted on a frame 80 that includes a pair of downwardly extendinglegs 81 (only one of which is shown). The legs 81 are supported from ascale beam 82 by knife edge fulcrums as at 84. The beam 82 hasrearwardly extending members 85 (only one being shown) that are in turnsupported by knife edge fulcrums as at 86 mounted on the frame 77. Therear portion of the beam supports a weight basket 87 through knife edgefulcrums as at 89. An adjustable beam stop 90 is mounted on the frame 77to limit the beam movement.

The frame 30 also includes an inclined member 91 connected to the legs81 at its lower end by a link 92. A plate 94 secured to the member 91has a series of spaced recesses 95 therein. A bag seat 96 is pivotal-1ymounted as at 97 on seat support link 99 that extends rearwardly thereofand has a cross-pin 100 that may rest in the recesses 95. By this means,the seat may be adjusted to support bags of different size in properfilling relation to the fill spout.

A pneumatic ram 101 is pivoted as at 102 to the member 91 and has itspiston rod pivoted to a crank arm 104 that is fixed to the bag seatpivot 97 whereby the ram may be actuated to pivot the seat 96 about theaxis of pivot 97 for a purpose to be described hereinafter.

The bin 76 has been shown with a conicalbottom which may have a cleanoutpipe 14 and valve 15 (not shown in FIG. 3) connected thereto at itsapex, as in FIG. 1. A primary air pad 105 is spaced from the bottom ofthe bin and primary air is fed by pipe 106 into the spaced therebetweento pass through the pad and into the bin. A secondary air pad 107similar to that of FIG. 1 is shown within the bin and connected to anair supply pipe 109.

It will be seen that the upper end of the bin 76 is closed by a plate110 having a central opening by which a hopper 111 communicates with thebin through a valve 112. The valve member or gate 114 for this sectionis controlled by a pneumatic ram 115.

As in the low head packer of FIG. 2, the bin 76 has a vent line 116extending between the top thereof and hopper 111, and a normally closedvent valve 117 is interposed in this line 116.

Referring now to FIG. 4, there is shown schematically a pneumaticcircuit for control of the various operating elements of the packer ofFIG. 3, and illustrating the condition of the circuit at the start of afilling operation, the solid lines representing pressurized lines andthe broken lines representing exhausting lines. Any suitable source ofcompressed air supplies such air to the line 120 which conducts the airthrough a filter and lubricator 121 -to a manifold line 122 which inturn is connected to a line 124 that leads to an air valve 125 of thesliding spool type. One end of the valve chamber communicates throughline 126 with a manual start button 127, while the other endcommunicates through lines 129 and 129a with a manual stop button 130and a scale stop button 130a, respectively. Depression of the manualstart button 127 exhausts one side of the chamber of valve 125 allowingthe spool to shift to the left to direct air through line 131 tocylinder 19 to open the fill spout, the cylinder exhausting through line132, the valve 125 and ex- 'haust134.

The valve 125 supplies pilot air through a t ap line 135 for theoperation of other valves in the system. Thus, the line 135 supplies airto the valve 136 which, in one position, established by pressure led tothe right side of its chamber through the lines 124, and 171, thereversal valve 172 and lines 174 and 175, completes communicationbetween the line 135 through line 137 with the chamber of a valve 139 soas to move the spool therein to the right, as viewed. This valve 139therefore establishes communication between manifold line 12.2, line140, and lines 141 and 142 to actuate a cylinder 144 to close the ventvalve 117 (FIG. 3); also from line 141 to line 145 to actuate thecylinder 67 (FIG. 2) to set the valves 54 and 62 to supply air asdesired to the primary and secondary pads; also to the bag clampcylinder 20 moving it into clamping position. It will be seen that thelefthand side of the chamber of the valve 136 exhausts through the line173 and reversal valve 172.

The opposite sides of each of these cylinders 144, 67 and 20 aresimultaneously opened to atmosphere through lines 142a, 145a and 141a,respectively, through the opposite side of valve 139. Meanwhile, thechamber of valve 139 exhausts through line 147, valve 136, lines 149,132, valve 125 and exhaust 134.

Simultaneously, air under pressure flows from line 137 into line at thecross-connector 151, thence through flow control 152 in the restricteddirection, accumulator 154, providing a predetermined delay in the airsignal, and line 155, to one side of the chamber of bag dischargecontrol valve 156 shifting the spool therein to allow air to flow fromthe supply line 120 through line 157 to bag discharge cylinder 101 (FIG.3).

At the same time, air flows from the cross-connector 151 through line159 to the chamber of the feed gate control valve 160, shifting thespool therein to allow air under pressure to flow from manifold line122, lines 161, and 162 to the feed gate control cylinder 115 (FIG. 3)to close the feed gate 114, the cylinder 115 exhausting through line162a and valve 160.

It will be seen that \as bag discharge control valve 156 communicatesthe start signal to the bag discharge cylinder, the chamber of thatvalve 156 exhausts through line 164, cross-connector 165, line 147,valve 136, lines 149 and 132, valve 125 and exhaust 134, while thecylinder 101 exhausts through line 157a, valve 156 and needle valvecontrol 158 that allows fine control of the bag discharge cylinderspeed. Also, as the spool in the feed gate control valve shifts to theright, as viewed, the chamber exhausts through line 166, accumulator167, line 169, flow control in the non-restricted direction,cross-connector 165, line 147, valve 136, lines 149 and 132 valve 125and exhaust 134.

If it is desired to operate a bank of several packers, the pressure line174 leading out of the reversal valve 172, maybe tapped by across-connector 168 to feed pressurized air to the right side of thechamber of a valve 136a similar to valve 136. A similar cross-connector168a enables air to be brought from cross-connector 168 through line 175to line to valve 136]), these valves exhausting through lines 176 and177, respectively, crossconnector 179, line 173 and reversal valve 172,and serving to control circuits similar to that just described, in thesame manner as does the control valve 136.

To summarize the operation of the control circuit,

upon the initiation of a start signal, the filling tube cutoff device 19moves to the open position allowing communication between the bin andthe bag; the bag clamp cylinder 20 is moved to clamp the bag on thespout; the air supply is delivered to the pads and 167 at predeterminedfiow rates, as described in connection with FIG. 2 for a fillingcondition; the vent valve 117 is closed; the feed gate 114 is closed;and then, after a delay of say two seconds, for example, determined bythe accumulator 154 and the flow control 152, the bag seat 96 isretracted to the position shown in FIG. 3.

The purpose for delaying retraction of the bag seat relates to thematter of assuring full opening of each bag. The bag, when mounted onthe fill spout, is not fully extended before the seat is retracted. Asfilling starts, a small amount of material enters the bag and, if thebag is not fully open (exemplary reasons for this having been stated),this material accumulates above the bag bottom. After a slight delay,and before an amount of material so accumulates sufficient to tilt thescale beam to cut-off position, the bag seat is quickly retracted,snapping the bag to its fully extended length and enabling theaccumulated material to drop towards the bottom of the bag, thusbreaking any bond of paste in its path. As mentioned, this amount ofmaterial will not be sufficient to tilt the scale beam to cut-01fposition.

Referring now to FIG. 5, there is shown schematically the same pneumaticcontrol circuit illustrated in FIG. 4, but showing the condition of thecircuit elements when a stop signal is initiated. In this view, as inFIG. 4, the solid lines represent the pressurized side of the circuitand the broken lines represent the exhaust side.

The stop signal may be initiated manually by depressing the stop button136 or automatically when the scale makes its weight by actuation of thebutton a by the scale beam. Upon actuation of either of these buttons,the spool of valve 125 moves to the right, as viewed, directing airunder pressure from line 124, through the valve and the line 132 to oneside of cut-off cylinder 1? to actuate the same to cut off the flow ofmaterial through the spout by closing the pinch tube 17 (FIG. 3). Theother side of cylinder 19 exhausts through line 131 the valve 125 andexhaust 134.

At the same time, air under pressure moves through the line 141, thevalve 136, line 147 and cross-connector 165 to the righthand side of thechamber of valve 139, as viewed, shifting the spool to the left, thusexhausting one side each of the cylinders 144, 67 and 20 through thelines 142, and 141, respectively, the valve 139 and the exhaust 138,thereby opening the exhaust valve 117 (FIG. 3), shifting the cylinder 67to regulate the air supply to the air pads as desired during down time,as explained with reference to FIG. 2, and opening the bag clamp.

Pressurized air, upon reaching the cross-connector flows through lines164 to the right side of valve 156 to shift its spool to the left, asviewed, whereby air from supply line 120 flows through the valve to line157a and one side of the bag discharge cylinder 101 thus tilting theseat 96 (FIG. 3) to discharge the bag from the fill spout, the oppositeside of this cylinder 101 exhausting through line 157, valve 156 andadjustable exhaust 158 which is set to slow the action of the cylinder101.

Air also flows from the cross-connector 165 through line 169, flowcontrol in the restricted direction, accumulator 167 providing apredetermined delay in the air signal, line 166 to the right side of thechamber of feed gate valve 160 thus shifting its spool to the left, asviewed, and enabling air under pressure in the manifold 122 to movethrough line 161, valve 160, and line 162a to the feed gate cylinder 115shifting the feed gate 114 (FIG. 3) to the open position to allow a newcharge of material to move from the hopper 111 to the bin 76, theopposite side of this cylinder 115 exhausting through the line 162 andthe valve 160. As the spools in the valves 139, 156

12 and 160 shift to the left the chambers exhaust through lines 137a,155 and 159 respectively, to the cross-connector 151 and thence throughline 137, the valve 136, lines 135 and 131, valve 125 and exhaust 134.

If a bank of packers are being used, the reversal valve 172 may beconveniently actuated to shift the positions of the spools in valves136a and 136b by directing pressurized air through the line 173 to thecross-connector 179 and thence through lines 176 and 177 to therespective chambers, the opposite sides of the chambers exhaustingthrough lines 174 and 180, respectively, along with the exhaust of valve136 through the line 175 and the reversal valve.

To summarize the operation of the control circuit upon the initiation ofa stop signal, the bag clamp moves to release position, the filling tubecut-off device is moved to the closed position stopping movement ofmaterial into a bag; the :air supply is delivered to the pads 105 and107 at predetermined flow rates as described in connection with FIG. 2for a down condition; the vent valve 117 is opened; the feed gate isopened, and the bag seat is tilted in a clockwise direction, as viewedin FIG. 3, but slowly because of the controlled exhaust through exhaust158 on valve 156, to discharge the full bag.

It is important to note that the circuit illustrated is exemplary only.Actually, any cylinder can be controlled in its speed of operation bydelaying its exhaust as, for example, by the adjustable exhaust valves158. Also, the signal to any valve can be delayed by use of a flowcontrol and accumulator in the particular line, as in the line 154), forexample. Such variations are not shown herein, because those personsskilled in the art, upon familiarizing themselves with the illustrativecircuits shown would be readily able to adapt the same to provide thedesired variations.

It is, therefore, within the concept of the present invention to delaythe operation of the bag discharge cylinder 101 after the initiation ofa stop signal so as to permit natural venting of the air in the bagthrough the bag itself, thereby to minimize the blowing of dust outthrough the bag valve when it and the filling spout are separated. Thiscould readily 'be accomplished by inserting a flow control andaccumulator in the bag discharge valve signal circuit on the stop side,for example.

It is also Within the present concept to delay the operation of thecut-off cylinder 19 in the stop side of the cycle until after theopening of the vent valve 117. This would enable the bag to vent backthrough the bin, thus giving a quick, clean operation. In fact, withsome materials, the cut-off can be eliminated altogether, the materialflow stopping immediately upon venting the bin pressure through thevalve 117.

Similarly, if desired, the opening of the cut-off could be gelayed inorder to pro-pressure the bin before starting to Another important partof the present contribution resides in the utilization of the vent valveto allow some venting of the bin to lower the pressure therein as thefilling portion of the cycle approaches its end. Thus, the speed of flowof material will be reduced to provide a dribble feed into the bag,giving fine weight control. The vent valve may also be used to raise thepressure in the bin to a relatively high value just before starting tofill, and then quickly dropping the pressure by opening the vent valvesimultaneously With the fill spout to obtain an effect similar to anexplosion in the bin, thereby creating a condition of excellent fluidityin the material. The vent valve would, of course, be immediately closedagain as packing begins.

It has been found that the present invention enables certain powderycompressible materials to be pro-compressed and actually extrudedthrough the filling spout into the bag. Where it is desired toaccomplish such packing the primary air may be shut off completely byclosing both of the variable orifices in the primary air supply line andraising the pressure of the secondary air to start the material flowing.In this connection it is important to note that with some materials ithas been found advantageous to utilize the control circuit so as to shutoff the primary air during filling and to turn it on during the downtime while a new bag is being applied. In this way, the down time isutilized to fluidize the material, so that when the spout is opened, thesecondary air can effect flow of the material through the spout withoutthe addition of air in the region of the spout, thus maintaining thematerial in the spout at a relatively high density. This technique maybe used with materials which retain for a period of time a sufiicientdegree of fluidity after the primary air is shut olT.

The circuit illustrated in FIGS. 4 and 5 may readily be adapted to theatmospheric packer of FIG. 1 simply by eliminating those elements thatare not needed such as the feed gate 114 and the vent valve 117, and thecontrols necessary for their operation.

If a bank of packers are being used, the present invention contributes amethod whereby they may be cleaned out most economically. The bags arefilled normally until the several bins have each less than a full bag ofmaterial remaining in them. Then, instead of cleaning each binseparately, thus wasting all of the material involved, the fillingspouts are closed, and the material is fluidized and moved into one ofthe bins, valved interconnections being provided for the purpose. Thisone bin is then used to fill more bags and, when less than a full bag ofmaterial remains therein, a bottom outlet, such as 14 in FIG. 1 isopened, the fill spout is closed, and the bin is pressurized, thusdischarging the remaining material.

It is to be understood that the term dry divided solid materials as usedherein, is not to be interpreted as excluding materials that have amoisture content, the criterion being the ability of the material to befluidized with a gas. In fact, such products as doughnut flour, themoisture content of which may run as high as and mixed molasses feeds,for example, come within the scope of the term.

Referring now to FIG. 6, there is shown a' graphical representation ofbin pressure plotted against the volurnetric flow rate of the air incubic feet per minute injected into an atmospheric type of packer, thatis, one having a bin which is open to the atmosphere and of the type asshown in FIG. 1. The graph of FIG. 6 illustrates the point that in suchopen or atmospheric type of packer it is possible to have a preselectedsuccession of volumetric flow rates but normally there is but a singleenergy level therein. However, such single energy level may not at alltimes exist but may in fact vary somewhat when the air flow rate ischanged.

As shown in FIG. 6, a curve 190 is employed for illustrating the changeof bin air pressure with change in volumetric air flow rate of thefluidizing air in an atmospheric type of packer which in this particularinstance does not have a secondary air supply, that is, an air supplyfor injecting air into the divided material which is located above theprimary or fluidizing source of air. The curve 190 has its beginningpoint at 191, the pressure rising substantially linearly up to theincipient point of fluidization at 192, then following such point, inthe direction of increased air flow rate, there exists a small hump 193characteristi of such pressure vs. air flow rate curves in this type ofpacker. The curve 190 thereafter at 190a is substantially level whichindicates the condition thatthe value of the volumetric air flow rate ofthe fluidizing air injected into this packer is selected to be between avalue not substantially in excess of that which occurs at the incipientpoint of fluidization 192 and a value which occurs below such point. Thepacker is cont-rolled whereby it is responsive to the condition that anincrease in volumetric air flow. rate of the fluidizing air beyond theaforementioned incipient point of fluidization produces insignificantchange in pressure in the bin in the region of the outlet. By soadjusting and so selecting the volumetric air flow rate asaforementioned the packer is controlled so that there is neither anexcessive infeed of material nor a starving infeed of such material intothe bin.

FIG. 7 shows schematically a bin ofthe open or atmospheric type, the binbeing designated 194 and having an outlet or container filling spout 195which is under the control of a valve 196 schematically shown here to beshut. Fluidizing air is directed into the bin from the bottom via an airpervious pad 197 which is fed thereto via a conduit 198 having twovalves 199 and 200 for controlling the air flow therethrough. By closingoff either one of these two valves the air flow through the conduit 198can be substantially diminished or by adjusting either one of thesevalves the flow rate through the conduit 198 can be adjusted.

FIG. 7 represents schematically the conditions in the bin when thefiilling tube or outlet 195 is closed, that is, when the valve 196 isclosed.

FIG. 8, on the other hand, represents the bin 194 when the filling tube195 has material passing therethrough by virtue of the opening conditionof the valve 196. Thus when the filling tube 195 is open and thefluidized material is flowing to and through the filling spout, adifferent pressure condition occurs. The pressure condition of FIG. 7 isrepresented by the point 201 on the curve which represents the energylevel of the material in the bin of FIG. 7 and this is the energy level,which it is desired to maintain in this particular packer, not only whenthe spout is closed, but also when it. is open.

But when the filling spout is open by the opening of the valve 196 andthe condition of FIG. 8 exists, then, in order to maintain the energylevel of point 201 (FIG. 6), it is necessary to diminish the supply ofair into the bin, for example, by shutting off one of the valves 199 or200 or by adjusting one of such valves. This, for example, reduces thevoulmetric air flow rate from the value 202 back to a value 203, and byvirtue of the falling movement of the divided particles downwardly inthe bin 194 there will be maintained or approximately the aforementionedenergy level at the point 201, this by virtue of the movement asschematically represented at 204, as shown in FIG. 8, which is symbolicof the activity of a particle while falling and moving toward thefilling spout 195. While it is desired to maintain the energy levelrepresented by the point 201 it is not always possible actually to stayon the target so to speak and to maintain this exact energy level. Hencewhen the volumetric flow rate is reduced to the value 203, the energylevel may not remain precisely at the point 201 but may be slightlyabove or below. Hence to this extent there may be a selected successionof energy levels in this atmospheric type of packer.

However, in the closed bin type of packer, such as that shown in FIG. 3,there is in fact a preselected succession of energy levels which issymbolized by FIG. 9 representing bin air pressure plotted against time,the packer having an infeed of the batch type, that is, increments orbatches of divided material are fed into the bin between each containerfilling cycle.

In FIG. 9 there is shown the curve 205 which starts at atmosphericpressure at point 206 and terminates at the end of the filling cycle atpoint 207 also at atmospheric pressure. This curve represents thechanges in pressure within a bin of the type as shown in FIG. 3 during atypical filling cycle.

In the cycle represented in FIG. 9, there is employed the so-calledprepressurizing technique wherein the bin is brought to a selectedrelatively high air pressure prior to the initiating of the filling ofthe container and such pressure is maintained substantially constantduring the filling of such container, with the exceptions noted below.

Thus at the outset of this particular cycle, namely, at the commencingpoint 206, the pressure in the bin is zero (or atmospheric) andthereatfer the pressure at first rises to substantially the valueindicated at 207:; which, for example, may be 2 p.s.i. and may remain atthis value up to point 208 at Which time the pressure rises relativelyabruptly, by virtue of the control of the volumetric air flow rate intothe packer, up to the starting point 209 of the container filling cycle.At this point the bin air pressure has achieved the target value, forexample, 10 p.s.i. Also, at this point when such target pressure hasbeen reached, the operator of the apparatus will press a startingbutton.

However, prior to this pressure having been reached and reverting to thepoint 208, at, for example, 2 p.s.i. within the closed bin, there mayautomatically occur the following: The bin is automatically closed bysuitable control means, namely, the valve (for example, the closure 11(FIG. 3)) is closed; also the exhaust valve, for example, 117 of FIG. 3is closed, and hence the pressure then can build up to the point 209 asaforementioned. The automatic closure of the bin by the closure of thevalves 114 and 117, that is, the closure of the exhaust valve and of thetop infeed valve, can be effected by means of a material level sensitivedevice in the bin or in response to time or alternatively in response topressure.

After the pressure has built up to the point 209 and the operator haspressed the button to start the container filling cycle, the fillingspout automatically opens by the opening of the valve of the fillingspout. Thereafter the bag fills in the manner aforementioned while thecurve 205 follows the substantially constant pressure region 205a whichin this case remains substantially at 10 p.s.i. during the filling ofthe bag. When the point 210 has been reached, the bag is filledwhereupon the spout is closed and the exhaust valve is opened.Alternatively, the exhaust valve may be opened in order to stop thefeeding but in this particular case the filling spout is closed and thevalves in the upper portion of the bin are opened thereby causing thesudden drop of the pressure to atmospheric, namely, to the point 207comprising the righthand extremity of the curve 205.

The curve to the right of the point 207 and between the points 207 and211 is designated by the numeral 212 and is substantially similar tocurve 205 in that a point 218 is reached which is analogous to 208, andalso a point 214 is reached which is analogous to 209 which signifiesthe starting of the container filling cycle by the opening of thefilling spout. However, during the container filling cycle, that is,while a container such as a bag is being filled, and in order to renderthe divided material more fluid, it is possible suddenly to drop thepressure in the bin by some selected increment, for example, from 10p.s.i. of the point 214 down to, for example, 8 p.s.i. of the portion ofthe curve designated by the numeral 215. Such dropping of the pressurewas initiated at point 216 by, for example, an opening of a valve in thetop of the bin. This opening of the valve and thus the lowering of thepressure is not enough to prevent an adequate flow rate but, asaforementioned, may be employed for artificially enhancing the fluidityof the material. Commencing at a point 217, the pres sure may be furtherdropped to the value 218 which is adequate for a dribble flow into thebag thereby achieving such a flow by a control of the valves of the binand not of the spout.

Following the completion of such dribble flow, the container or baghaving received the selected weight of material, the filling spout isclosed and the pressure is abruptly dropped to the point 211(atmospheric) of FIG. 9 simultaneously with the opening of, for example,the bin exhaust valve and also the top infeed valve of the bin.

Referring now to FIG. 10, there are illustrated several curves forindicating the pressurizing of the closed type of bin having the batchtype of infeed, such pressurizing being accomplished by the injection ofair well above the level of the outlet and by means of the socalledsecondary or top air. The pressurizing of such batch infeed type ofpacker of the closed pressurized type is not in this form of theinvention accomplished by primary air and in fact it is one of theobjectives of this form of the invention to avoid the pressurizin-g ofthe bin by such primary or fiuidizing air which is fed into the bin viathe lowermost air previous membrane. The employment of the so-calledprimary or fluidizing air for the pressurizing of this type of packerhas not proved satisfactory because it has over-aerated the material andit has slowed down the filling time substantially.

The overaeration occurs principally in the bin and in an undesiredlocation near the filling tube if such primary or fluidizing air isemployed for the pressurizing of the bin.

It is necessary to inject into this type of bin large volumes of air tocause it to reach the desired pressure during the container fillingcycle and since it has been found disadvantageous to inject thesevolumes of air via the lowermost air previous membrane, suchpress-urizing air is directed, for example, via the element 107 (FIG. 3)above the level of the membrane 105.

When such air via the secondary air injecting means 107 is employed forthis purpose in the batch infeed type of packer, it is scheduled to flowinto the packer, that is, it is fed into the packer at a selectedvolumetric flow rate as shown, for example, in FIG. 10 which is a plotof air pressure in the bin against time. FIG. 10 indicates, by way ofexample, a pressure of 2 p.s.i. in the bin initially up to the containerfilling cycle starting point 219, the latter being the righthandextremity of the initial portion 220 of this graphical representation.

At the point 219, the initiation of the container filling cycle takesplace, for example, by the pressing of a starter push button on thepacker, at which time air under pressure is fed in at the upper regionof the bin via the upper conduit system, for example, via the conduit109 and the upper or secondary air membrane 107 (FIG. 3). Such air canbe fed into the closed bin at selected volumetric flow rate and, forexample, this can be 50 c.f.m. which products the curve 221 and whichhas a gradual pressure gradient prior to the reaching of a selectedtarget pressure in the bin, for example, 10 p.s.i.

Alternatively, the volumetric air flow rate can be much higher, forexample, 200 c.f.m. which produces the curve 222 which is ofsubstantially greater slope, the target pressure of 10 p.s.i. beingreached early in the container filling period.

By Way of comparison, an atmospheric or open bin type of packer of thisclass may produce a pressure vs. time curve, as indicated at 223, which,due to a pccularity, has a slight dip or depression at 223a.Alternatively, reverting to a closed batch infeed type of packer of thetype shown in FIG. 3, it is possible to inject the air into the upperregion of the material via the secondary air injection means, such as107, thereby to produce the line 224 which is at or near the initialpressure of 2 p.s.i. This may be desirable with certain types ofmaterial, for example, in tfilling an asp-halt lined bag, or any bag,with a fluid or air impervious lining and which type of bag may be used,for example, for containing a hygroscopic type of material requiringthis kind of protection.

Thus in the batch infeed type of pressurized packer which is closed tothe atmosphere during the container filling cycle, it is possible toselect the volumetric flow rate of the air into the bin and this shouldbe directed therein via the upper or secondary air injecting means andnot via the lowermost air pervious membranes at the bottom of the bin.

Assume, for example, that a common conduit directs air to the closedtype of bin of FIG. 3, this common conduit being in communication withthe conduits 106 and 109. Such common conduit directs air under pressureto the bottom portion of the bin and thus also to the upper regionthereof. The air flow rate to the bottom early in the filling cycledrops substantially to zero and such air follows the path of leastresistance and the bulk of its volume thereupon is directed to the upperregion of the bin via the secondary air injecting means 107.

Reverting to the curve 222 (FIG. 10), there is illustrated that thehigher volumetric flow rate into the bin, for example, 200 c.f.m.,shortens the filling time, there being indicated .a container fillingcycle over the span 225 as opposed to the length of such filling timewhen the flow rate is 50 c.f.m. as indicated by the curve 221 and whichis over a slightly longer span 226.

The curves of FIG. 10 represent what may be termed a pressure transientperiod which refers to the period of changing pressure in the bin duringthe time of the filling of the container. Such transient period,referring to the steep portion of the curve 222, would be during thetime span 227, namely, from the point of the 2 p.s.i. pressure at 219 upto the point 228 Where the pressure in the bin reached its target value,for example, 10 p.s.i. and there became stabilized.

However, with respect to the other curve 221, the transient period isrepresented by the time span 229 which is slightly less than the span226 and represents the length of time required from the starting of thefilling cycle at point 219 up to the point where the pressure in the binreached the target value, namely, 10 p.s.i.

Although it has been found advantageous to inject the principalpressurizing air flow into the bin via the secondary air injectingmeans, that is, means located as in FIG. 3 above the level of the lowermembrane 105 and the tube 106, this is applicable only to the batchinfeed type of packer which is closed to the atmosphere during thecontainer filling time and is not applicable to the continuous infeedtype of packer, such as that shown in FIG. 2. In fact, it is desirableto achieve the desired pressure in the type of packer of FIG. 2 via theair previous pad in the bottom of the bin although this embodiment ofthe invention is not limited to this characteristic. The reason for thisis that it is possible to pressurize with air the continuous infeed typeof bin at relatively low flow rates, the bin already having beenpressurized and it is only required to add or inject into the bin avolumetric air flow rate that is being lost due to the infeed of dividedmaterial or, for example, due to a leak past the material infeed valveplus whatever volume of air is being lost during the filling.

Assume, for example, that the target value of pressure within the bin ofthe type of FIG. 2 is 10 p.s.i. and it is desired to maintain itcontinuously at this pressure despite a continuous infeed of dividedmaterial via the top of the bin. For example, there may be required avolumetric air flow rate of injection into the bin of 1 c.f.m. Thispreferably should be done via the air pervious pad in the bottom of thebin because it facilitates the maintenance of the fluidity of thedivided solid material in the bin. While such 1 c.f.m. is desirable tobe fed into the bin via its bottommost air pervious membrane, thisinjection of air may not be adequate to maintain the target pressure of10 p.s.i. This may be because there is a leak past the infeed valve 50of, for example, 5 c.f.m. which will require additional air to be fedinto the bin in order to maintain the pressure. Thus, for example, anadditional 4 c.f.m. may be added and this can be done via the secondaryair injecting means in the upper part of the bin as by the air perviousmembrane 51.

In lieu of an air leak past the infeed valve, as aforementioned, theremay be an escape of air past an adjustable exhaust passage, for example,69, and this may be in an amount, for example, of 1 c.f.m.

It is, of course, possible to have an injection of air into the bin forboth fluidizing the divided material and pressurizing the bin and in theamount of l c.f.m., via the air pervious pad in the bottom of the bin toreplace a loss of air of 1 c.f.m. at the top or upper region, thispresupposing that there is no air leakage past the main infeed valve inwhich event there would be no need to add an additional volume of airvia the secondary or upper air injecting means.

From the foregoing description, it will be seen that the presentinvention contributes a method and apparatus for packaging dry dividedsolid material quickly, efiiciently, with a minimum of air at thefilling spout so that the material enters the bag in a dense state, witha minimum of dusting and with uniform bag weights; but most important,the present concept enables the accomplishment of such packaging for anextremely wide range of materials. For example, the batch packer of FIG.3 has been used in tests to successfully package materials ranging from6 pounds per cubic foot up to approximately pounds per cubic foot, andwith particle sizes ranging from 400 mesh and finer up to inch pellets.Most bags can be packed with a free top as low as l to 1% inches.

Reverting to the batch feed type of packer shown in FIG. 3, a preferredmethod of operating the same in the filling of bags with thefiuidizable, comminuted material is as follows. Assume at the start ofoperations, the bin 75 is completely empty. The vent valve 117 is set atthe open position to vent the bin to atmosphere, and air underfiuidizing pressure is continuously introduced through the lower airpressure line 106 and the fluidizing air pad, this pressure being suchas to produce a relatively low pressure in the comminuted material ofabout 2 p.s.i. as represented by the line 208 in FIG. 9. The bin inletvalve 114 is now opened and a batch of the comminuted material chargedfrom the upper storage bin 111 into the lower bin 75. Before the bin 75is completely filled, however, the vent valve 117 is closed to preventthe comminuted material from entering and possibly plugging the ventline 116. When the bin 75 is filled to the desired extent, the inletvalve 114 is closed, and supplemental air under pressure is introducedthrough the upper air inlet pressure line 109 until the pressure hasbuilt up to a relatively high value of, for example, 10 p.s.i., asindicated by the point 209 of FIG. 9. At this point the filling cycle isinitiated by depressing the start button to open the outlet valve 19 ofspout 16 and thus fill a bag attached to the spout. When the bag isfilled to the preselected weight, the valve 19 of the filling spout 16is closed as is also the valve supplying the air to line 109, this beingthe valve corresponding to valve 64 of FIG. 2. The vent valve 117 isalso opened to vent the bin 75 to atmospheric pressure, and the fillingcycle thereafter repeated for the next bag filling as above described.

While the invention has been described in detail with respect to apreferred embodiment, it will be understood by those skilled in the artthat various modifications may be made without departing from the spiritand scope of the invention and it is intended to cover all such changesand modifications in the appended claims.

We claim:

1. A method for packaging dry divided solid material comprising:introducing material to be packaged into bin means having a materialdischarge outlet, introducing air under pressure into said bin means inthe region of said discharge outlet to fluidize the material in said binmeans, opening said material discharge outlet while shutting off saidfluidizing air, and admitting air under pressure into said bin means ina region above said first mentioned region in an amount greater than isrequired for fluidizing, the surplus air effecting compression of thematerial at the discharge outlet without prejudicing the flowability ofsaid material out of said bin means through said material dischargeoutlet.

2. A method for evacuating a plurality of interconl9 nected bins eachhaving dry divided solid material in an amount insufficient toconstitute a package thereof and each having a package fill spout and atleast one of said bins having a normally closed clean-out opening, saidmethod comprising: fluidizing the material in some of said bins andcausing it to flow into one of said bins having a clean-out opening toincrease the amount of material therein, closing the interconnectionbetween bins, discharging said material through the fill spout of saidone bin into containers therefor until an amount remains in said bininsutficient to constitute a package thereof, opening said clean-outopening, and pressurizing said bin to cause said remaining materialtherein to flow out through said clean-out opening.

3. The method of dispensing fluidized comminuted material by means of anapparatus comprising a closed bin having an upper charging inlet andclosure means therefor, and a normally closed lower dispensing outlettogether with a first air injection and fluidizing means adjacent saidoutlet and a second air injection means disposedabove said outlet, saidmethod comprising the steps of: charging said material through saidinlet while injecting air under pressure through said first airinjecting means at a volumetric rate such as to fluidize said material,opening said outlet to discharge said material, and while said outlet isopen, injecting suflicient supplemental air under pressure through saidsecond air injection means to compress said material at said dispensingoutlet.

4. The method of dispensing fluidized, comminuted material by means ofan apparatus comprising a closed bin having an upper charging inlet andclosure means therefor, and a normally closed lower dispensing outlet,together with a first air injection and fluidizing means adjacent saidoutlet and a second air injection means disposed above said outlet, andmeans independent of said inlet and outlet for venting said bin toatmospheric pressure, said method comprising the steps of: charging saidmaterial through said inlet while injecting air under pressure throughsaid first air injection means at a volumetric rate such as to fluidizesaid material, opening said outlet to discharge said material, and whilesaid outlet is open, injecting sufficient supplemental air underpressure through said second air injection means to effect compressionof the material adjacent said lower dispensing outlet, and venting saidbin to atmospheric pressure after a preselected weight of said materialhas been dispensed.

5. The method of dispensing fluidized, comminuted material by means ofan apparatus, comprising a closed bin having a normally closed uppercharging inlet and a normally closed lower dispensing outlet, togetherwith a first air injection and fluidizing means adjacent said outlet anda second air injection means disposed above said outlet, said methodcomprising the steps of: opening said inlet, charging a batch of saidmaterial therethrough and closing while injecting air through said firstmeans at a rate to fluidize said material, opening said outlet todispense said material and While so doing injecting surplus supplementalair under pressure into said bin through said second air injection meansthe surplus air etfecting compression of the material at the lowerdispensing outlet without prejudicing the flowability of said material.

6. The method of dispensing fluidized, comminuted material into acontainer by means of an apparatus comprising a closed bin having anormally closed upper charging inlet, a normally closed lower dispensingspout, and normally closed bin venting means together with a primary airinjection and dispersing means adjacent said outlet, and secondary airinjection means disposed above said outlet, said method comprising thesteps of: injecting air through said primary means at a rate to fluidizesaid material, opening said inlet, charging a batch of said materialtherethrough and closing, opening said spout with said containerattached and injecting surplus air through said secondary means fordischarging compressed material into said container to a preselectedweight, and prior to attainment of said weight, opening said ventingmeans 2% to atmospheric pressure to dribble-feed said material untilsaid preselected weight is attained, and thereupon closing said spoutand discontinuing said secondary air injection.

7. The method of dispensing fluidized, comminuted material into acontainer by means of an apparatus comprising a closed bin having anormally closed upper charging inlet, a normally closed lower dispensingspout, and normally closed bin venting means together with a primary airinjection and dispersing means adjacent said outlet, and a secondary airinjection means above said outlet, said method comprising the steps of:injecting air through said primary means at a rate to fluidize saidmaterial, opening said inlet, charging a batch of said materialtherethrough and closing, opening said spout with said containerattached and injecting air through said secondary means for densifyingand thence discharging said material into said container to apreselected weight, and thereupon opening said venting means toatmospheric pressure, closing said spout and discontinuing saidsecondary air injection.

8. The method of dispensing fluidized, comminuted material into acontainer by means of an apparatus comprising a closed bin having anormally closed upper charging inlet, a normally closed lower dispensingspout, and normally closed bin venting means together with a primary airinjection and dispersing means adjacent said outlet, and a secondary airinjection means above said outlet, said method comprising the steps of:injecting air through said primary means at a rate to fluidize saidmaterial, opening said inlet, charging a batch of said materialtherethrough and closing, opening said spout with said containerattached and injecting suflicient air through said secondary means forcompressing the material at at least in the region of the lowerdispensing spout and for discharging said material into said containerto a preselected weight, thereupon opening said venting means toatmospheric pressure, closing said spout and discontinuing saidsecondary air injection, thereupon again opening said inlet to charge asecond batch of material into said bin, closing said venting means priorto completion of said charge, and closing said inlet upon completion ofsaid charge.

9. The method of dispensing fluidized, comminuted material by means ofan apparatus, comprising a bin therefor having a normally closed lowerdispensing outlet and fluidizing air injection and dispersing meansadjacent thereto, said method comprising the steps of: charging saidmaterial into said bin, injecting air under pressure into saidfluidizing means at a volumetric flow rate sufficient to fluidize saidmaterial with said dispensing outlet closed, opening said outlet todispense said material, and while said outlet is open, injecting airthrough said fluidizing means at a different volumetric flow rate suchas to maintain said material fluidized while discharging the samethrough said outlet.

10. The method of dispensing fluidized, comminuted material by means ofan apparatus comprising a bin open to atmospheric pressure and having anormally closed lower dispensing outlet, together with means forinjecting air under pressure into the base of said bin, said methodcomprising the steps of: charging said bin with said material with saidoutlet closed and injecting air into said material at a pressuresuflicient to fluidize said material but insufficient to produce boilingthereof, opening said outlet to discharge said material and while saidoutlet is open, reducing said air pressure to a value such as tomaintain substantially the same state of fluidization of said materialas obtained at the higher pressure aforesaid with said outlet closed.

11. The method of dispensing fluidizable, comminuted material into acontainer by means of an apparatus comprising a closed bin having anormally closed upper charging inlet, a normally closed lower dispensingoutlet, and

normally closed bin venting means, together with means for in ecting anddlspersing fluidizing air under pressure into said bin, which comprises:opening said inlet and charging a batch of said material into said binwhile inectlng arr therein at a rate to establish a relatively low airpressure in said material, closing said inlet and increasing the airpressure Within said bin to a relatively high pressure, opening saidoutlet to discharge a batch of said material into said container whilemaintaining said relatively high air pressure within said bin, closingsaid outlet when said container is filled to a preselected extent andventing said bin substantially to atmospheric pressure while reducingthe rate of air injection into said bin.

12. The method of dispensing fluidized, comminuted material into acontainer by means of an apparatus comprising a closed bin having anormally closed upper charging inlet, a normally closed lower dispensingspout, and normally closed bin venting means together with a primary airinjection and dispersing means adjacent said outlet, and a secondary airinjection means above said outlet, said method comprising the steps of:injecting air through said primary means at a relatively low rate tofluidize said material, opening said inlet, charging a batch of saidmaterial therethrough and closing, opening said spout with saidcontainer attached and injected air through said secondary mean-s topressurize said bin to a relatively high value for discharging saidmaterial into said container to a preselected weight, and thereuponopening said venting means to atmospheric pressure, closing said spoutand discontinuing said secondary air injection.

13. The method of dispensing fluidized, comminuted material into acontainer by means of an apparatus comprising a closed bin having anormally closed upper charging inlet, a normally closed lower dispensingspout, and closeable bin venting means, together with a primary airinjection and dispersing means adjacent said outlet, and a secondary airinjection means above said outlet, said method comprising the steps of:injecting air through said primary means at a rate to fluidize saidmaterial, opening said inlet with said bin venting means open andcharging a batch of said material into said bin, closing said binventing means before said bin is filled and thereupon closing saidinlet, thereupon opening said spout with said container attached andinjecting air through said secondary means to pressurize said bin to arelatively high pressure for rapidly discharging said material into saidcontainer to a preselected weight, thereupon opening said venting meansto atmospheric pressure, closing said spout and discontinuing saidsecondary air injection, and repeating said method for the filling ofadditional containers.

14. The method of dispensing fluidized, comminuted material into acontainer by means of an apparatus comprising a closed bin having anormally closed upper charging inlet, a normally closed lower dispensingspout, and normally closed bin venting means together with a primary airinjection and dispersing means adjacent said outlet, and secondary airinjection means disposed above said outlet, said method comprising thesteps of: injecting air through said primary means at a rate to.fluidize said material, opening said inlet, charging a batch of saidmaterial therethrough and closing, opening said spout with saidcontainer attached and injecting air through said secondary means at arate to establish a relatively high pressure in said bin for rapidlydischarging said material into said container to a preselected weight,and prior to attainment of said weight reducing the pressure in said binto a value such as to dribble-feed said material until said preselectedweight is attained, and thereupon opening said venting means, closingsaid spout, and discontinuing said secondary air injection.

References Cited by the Examiner UNITED STATES PATENTS 1,979,492 11/1934Russell 14168X 2,221,741 11/ 1940 Vogel-Jorgensen 302-53 2,681,748 6/1954 Weller 222-195 2,792,262 5/ 1957 Hathorn.

2,887,292 5/1959 Titc-henal 222-495 X 2,905,362 9/1959 Aust 222-195 X2,922,611 1/1960 Aust 177--1 2,936,994 5/ 1960 Lau 141-68 X 3,073,4011/1963 Zenke 177-63 FOREIGN PATENTS 1,096,189 1 2/1954 France.

LAVERNE D. GEIGER, Primary Examiner. LOUIS J. DEMBO, Examiner.

N. STACK, E. EARLS, Assistant Examiners.

1. A METHOD FOR PACKAGING DRY DIVIDED SOLID MATERIAL COMPRISING:INTRODUCING MATERIAL TO BE PACKAGED INTO BIN MEANS HAVING A MATERIALDISCHARGE OUTLET, INTRODUCING AIR UNDER PRESSURE INTO SAID BIN MEANS INTHE REGION OF SAID DISCHARGE OUTLET TO FLUIDIZE THE MATERIAL IN SAID BINMEANS, OPENING SAID MATERIAL DISCHARGE OUTLET WHILE SHUTTING OFF SAIDFLUIDIZING AIR, AND ADMITTING AIR UNDER PRESSURE INTO SAID BIN MEANS INA REGION ABOVE SAID FIRST MENTIONED REGION IN AN AMOUNT GREATER THAN ISREQUIRED FOR FLUIDIZING,